Disallowed MIME type error when testing in browser

Thanks for putting this example together.

**Describe the bug**
Running the example creates browser errors. Generated script tries to load wasmbuild package TypeScript files.

**To Reproduce**
I clone the repo and follow instructions in README. Instead of expected result in the browser console, I see errors from trying to load TypeScript files included in the generated wasm script:

```
Loading module from “https://deno.land/x/wasmbuild@0.15.0/cache.ts” was blocked because of a disallowed MIME type (“application/typescript”).
Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://deno.land/x/wasmbuild@0.15.0/cache.ts. (Reason: CORS request did not succeed). Status code: (null).
```

Similar issues seen in Chrome and Firefox.

**Expected behaviour**
Expect `3` to be printed to the browser console.

**Additional context**
Errors come from attempting to load TypeScript in these two lines in generated WASM (`lib/rs_lib.generated.js`):

```javascript
import { Loader } from "https://deno.land/x/wasmbuild@0.15.0/loader.ts";
import { cacheToLocalDir } from "https://deno.land/x/wasmbuild@0.15.0/cache.ts";
```

I see the same issue in wasmbuild versions 0.12 to 0.15, though version 0.11.0 outputs the expected result.

Is there a way to generate browser compatible code, with the latest wasmbuild versions?

Thanks